As you're swiping your boarding pass ( or smartphone), the machine also scans it for particle-sized traces of explosive materials and sends the all-clear or no-go in less than two seconds.
In addition, you should consider avoiding plaintext-password network services: The POP3, FTP, and Telnet daemons pose a special risk because their passwords pass unencrypted across the open network, sniffable by any nearby machine along the way.